SettingsUsernameNTUSERDAT

SettingsUsername is a configuration or profile field in software applications that specifies the primary identifier used to sign in to an account and to label the user within the system. It is typically distinct from the display name and from the email address. In many systems, the username is immutable after account creation and must be unique across the service; some systems allow changes but require verification and may trigger conflicts or history preservation.

Validation rules vary by product. Common constraints include allowed characters (letters, digits, underscores, hyphens or periods), a minimum and maximum length, and the prohibition of reserved words or offensive terms. Whitespace is often disallowed or discouraged, and case sensitivity differs by implementation (for example, usernames may be treated as case-insensitive while stored verbatim).

Privacy and security considerations include the visibility of usernames in public profiles or URLs. Many platforms separate login credentials from publicly visible identifiers, and implement protections such as rate limiting, monitoring for enumeration, and optional two-factor authentication.

From a design perspective, username fields should provide helpful input controls, such as real-time validation, availability checks during creation, and clear messaging about constraints and consequences of changing the username. Database schemas typically enforce a unique constraint and may normalize or index the value for efficient lookups.

See also: Display name, Email, Password, Authentication, User profile, Account settings.